Study of emission episodes of urban aerosols by ion beam analytical techniques

The quantitative elemental composition and morphology of over 500 atmospheric aerosol particles were determined by nuclear microscopy and scanning electron microscopy (SEM). The samples originated from eight sampling campaigns, when hourly variation and sources of the urban aerosol elemental components were studied in Debrecen between 2007 and 2010. Aerosol which could be connected to heavy metal pollution episodes and high aerosol pollution levels deposits were selected for the nuclear microprobe study.Ion beam analytical methods (micro-PIXE and STIM) provided the elemental composition of coarse (particles with aerodynamic diameter between 2.5 and 10 μm) aerosols while the morphology of the different particle types was determined by SEM.Through the elemental composition, elemental correlations and morphology different particle types were identified and attributed to different anthropogenic sources like biomass burning, oil combustion, traffic or industry.     

环境气溶胶的核孔膜、扫描电子显微镜和微电子探针研究

用云母核孔膜、扫描电子显微镜和微电子探针对工艺房间空气中悬浮的气溶胶进行了采集 ,并对气溶胶的粒径分布、微粒形态及结构、元素成分和捕集机制进行了研究。     

PIXE和XRF用于北京新镇地区PM2.5源解析研究

大气颗粒物(APM)对人体健康和环境的影响越来越受重视,我国增设了PM2.5标准,同时提出了大气污染的专项治理措施。本文采用GENT二级取样器在北京郊区新镇进行连续取样,并用质子激发X射线荧光分析和能量色散X射线荧光分析对北京新镇地区收集到的140个大气颗粒物样品进行了多元素分析,对测量数据进行了可靠性评价和数据重组,结合取样、气象等参数建立了新镇地区大气颗粒物污染成分数据库,利用正矩阵因子模型进行污染源解析研究。初步认定了5个主要污染源,即燃煤源(29.2%)、汽车尾气和垃圾焚烧源(26.2%)、建筑工业源(23.3%)、土壤源(15.4%)以及含氯工业源(5.9%)。并结合气象数据进行了污染源来源研究,根据条件概率函数和潜在源贡献函数的计算结果作出了污染源来源分布图,发现污染来源与周围环境基本符合。     

The enhanced aerosol deposition by bipolar corona discharge arrays

The corona discharges provide an efficient way to induce precipitation or eliminate fog by increasing ion density in the open air.In this paper,one bipolar corona discharge array (positive and negative high voltage coupled simultaneously) which can generate high densities of positive and negative ions is developed.The comparison between bipolar corona discharge array and unipolar corona discharge array (positive or negative coupled only) indicates that bipolar corona discharge array can generate ～3 times higher ion density than unipolar corona discharge array.More charged aerosols are produced through collisions between ions and aerosols.The collision rate between aerosols is increased substantially by the attractive forces between positively and negatively charged aerosols.The deposition of aerosols induced by bipolar discharges is 25.7％higher than that of unipolar discharges at the humidity super-saturation condition.Therefore,the bipolar corona discharge system is a new option for the large scale ion sources used for artificial weather modification.     

我国部分省份环境气溶胶中239+240 Pu的测定

采用阴离子交换树脂分离结合α谱仪测量的方法对我国7个省份环境气溶胶中^239+240Pu含量进行测定,实验全程回收率为60.8%～94.6%,对气溶胶中^239+240Pu的最小可探测限为0.008 μBq/m³。普通环境气溶胶采样量需要达到30 000 m³以上,在应急情况等特殊环境气溶胶采样量为10 000 m³可满足要求。一般情况下气溶胶中²¹⁰Po含量比^239+240Pu高4～6个数量级,在分析和测量中要关注²¹⁰Po对^239+240Pu测量的影响。测量结果显示,我国普通省份环境气溶胶中^239+240Pu含量为0.009～0.099 μBq/m³,与美国、韩国和西班牙等国家空气气溶胶中的Pu含量处于同一水平。     

中子活化分析在煤质分析中的应用

利用中子活化分析方法对云、贵、川三省部分原煤中的常量、微量及有害元素的含量进行了检测、获知燃煤中主要的固态有害元素的大致分布情况,对防治由燃煤引起的大气污染起到了积极的作用。同时介绍了原煤燃烧前后大部分固态元素的变化规律。     

On a generalization of the Telford equation for aerosols

A linearized form of the coagulation equation for aerosols, known as the Telford equation, has been generalized to include diffusion, deposition, settling and condensational growth. The relationship between this equation and those of linear gas kinetic theory and neutron diffusion is elucidated and clarified. The linearized equation is shown to be useful for studying dilute radioactive aerosols and can be of value in following the consequences of a minor accidental release in a reactor environment. The linearity of the equation makes it amenable to many standard analytical and numerical solutions and it has great advantages over the conventional non-linear aerosol coagulation equation.Several exact, analytical solutions are obtained for the space-time-volume distribution function following a localized, pulsed release of monodisperse aerosol.     

Depth profiling of hydrogen in amorphous media and applicable to quartz air filters

We have explored the use of proton–proton coincidence, at proton energy of 6.35 MeV, for hydrogen determination and depth profiling in amorphous media. The method has been applied to quartz air filters. This non-destructive method is highly specific to hydrogen, depending only on the energy-loss distribution in p–p scattering events. The method, combined with other techniques, can be used to measure the total amount and depth distribution of particulate organic matter in aerosols on quartz air. The results for ambient air quartz filters show that the technique can separate several kinds of gaseous organic artifact, one of which cannot be corrected through the standard use of tandem quartz filters.     

Fukushima Daiichi fuel debris retrieval: results of aerosol characterization during laser cutting of non-radioactive corium simulants

ABSTRACT

The production and dispersion of contaminated aerosols during the laser cutting of corium can potentially provide useful insights into the dispersion of contamination during the evacuation of damaged reactors during decommissioning. Quantitative assessments of contamination dispersion are fundamental to the development of a safety case for the decommissioning of the Fukushima Daiichi plant. This collaborative work between IRSN, ONET Technologies and CEA, managed by the Mitsubishi Research Institute on behalf of the Japanese Ministry of Economy, Trade and Industry, presents the characterization of aerosols generated during laser cutting of corium simulants both in air and under water.

The objective is to obtain quantitative data for risk assessment related to the contamination released and disseminated when implementing this technique, over the next few years, in the process of decommissioning the damaged reactors. This paper presents a part of the results stemming from this project, focused on the characterization of aerosols produced during laser cutting of two representative corium simulants in air and underwater conditions. The experimental configuration also enabled investigation of the production of other material residues such as particle dross and water purity on the particulate composition of the aerosols. Ultimately, the radioisotope concentration distribution in the aerosols are transposed to radioactivity in order to assess the risk to radiation workers during decommissioning.     

PIXE investigation of aerosol composition over the Zambian Copperbelt

Atmospheric sulphate aerosol concentrations are of interest in climate change studies because of their negative climate forcing potential. Quantification of their forcing strength requires the compilation of global sulphur emission inventories to determine the magnitude of regional sources. We report on measurements of the ambient aerosol concentrations in proximity to a copper refinery in the central African Copperbelt, along the border of Zambia and the Democratic Republic of the Congo. This region is historically regarded as one of the largest African sources of sulphate aerosols. Sulphate is produced by oxidation in the atmosphere of SO₂ emitted during the pyrometallurgical processing of Cu–Co sulphide ores. Since the last quantification of sulphur emissions (late 1960s), there has been large-scale reduction in copper production and more frequent use of the leaching technique with negligible sulphur emissions.

Samples were collected over four weeks, November–December 1996, at Kitwe, Zambia. A low volume two-stage time-resolving aerosol sampler (streaker) was used. Coarse and fine mode aerosols were separated at >2.5 and >10 μmad. Hourly elemental concentrations were determined by 3.2 MeV PIXE, and routinely yielded Si, S, K, Ca, Ti, Mn, Fe, Cu and Zn, above detection limits. Si, K, Ca and Fe (major crustal components) dominated the coarse elemental mass. In the fine stage, S and Si accounted for up to 80% of the measured mass, and S alone up to 60%. Time series analysis allowed the division of sulphur and crustal elements (Si, K, Ca, Fe) between (i) background concentrations representative of synoptic scale air masses; and (ii) contributions from local sources, i.e., copper smelter and re-suspended soil dust. Short duration episodes of S concentrations, up to 26 μg/m³, were found simultaneously with enhanced Cu, Fe and Zn. Contributions from individual pyrometallurgic processes and the cobalt slag dump could be distinguished from the elemental signatures. Periods of diminished sulphur concentrations were also identified, indicating a well-mixed regional air mass. These results will contribute towards validating global climate model predictions of aerosol forcing over central Africa.     

江苏省城市放废库辐射环境监测水平研究北大核心CSCD

随着核技术在各领域的广泛应用,辐射环境的安全受到越来越多的重视。以江苏省城市放废库为研究对象,从2015年起连续对放废库进行辐射环境监测6年。对放废库周围的γ辐射空气吸收剂量率,水源水中总α、总β以及土壤中放射性核素进行了监测,并对辐射监测结果进行了分析。研究结果表明γ辐射空气吸收剂量率敏感点范围为59.0~96.5 nGy/h,源库四周范围为81.92~103.32 nGy/h;水源的总α和总β范围分别为0.90×10^(-2)~5.87×10^(-2)Bq/L和3.00×10^(-2)~16.00×10^(-2)Bq/L。γ辐射空气吸收剂量率的变化主要与源库的距离和废源的管理有关;水体中放射性水平变化主要与年降水量有关;土壤中核素的变化主要与放射性气溶胶有关。所有变化均在本底范围内涨落,对环境几乎没有影响,可以确保辐射环境安全。     

北京市某工业小区大气环境总量控制估算

本文利用Ａ值法对北京市某工业小区大气环境总量控制进行了估算。提出了实施工业小区大环境总量控制、总量优化分配的步骤方法。在衽总量控制后,以地面浓度估算为基础,考虑到污染源规划布局、经济利益、可行性等因素。对污染源分布规划方案进行适当调整。改善工业区大气环境质量、确保区域大气环境保护目标的实现,从而使工业小区经济、社会和环境得到可持续发展。     

Biological monitoring of toxic metals – steel workers respiratory health survey

The aim of this work is to search for respiratory system aggressors to which workers are submitted in their labouring activity. Workers from one sector of a steel plant in Portugal, Siderurgia Nacional (SN), were selected according to the number of years of exposure and labouring characteristics. The work reports on blood elemental content alterations and lung function tests to determine an eventual bronchial hyper-reactivity. Aerosol samples collected permit an estimate of indoor air quality and airborne particulate matter characterisation to further check whether the elemental associations and alterations found in blood may derive from exposure. Blood and aerosol elemental composition was determined by PIXE and INAA. Respiratory affections were verified for 24% of the workers monitored. There are indications that the occurrence of affections can be associated with the total working years. The influence of long-term exposure, health status parameters, and lifestyle factors in blood elemental variations found was investigated.     

某铀尾矿库周边土壤中铀元素的空间分布与污染评价

为查明某铀尾矿库周边土壤中铀元素的空间分布特征及污染程度,对该铀尾矿库进行了现场采样,利用便携式XRF元素分析仪进行了原位测试,并采用SPSS软件对铀元素的测试数据进行了统计分析。结果表明:该铀尾矿库周边土壤中铀元素含量的平均值分别是中国及其所在省土壤中铀元素含量背景值的4倍和2.3倍,而样品中铀元素含量变异系数达到61.84%,属于强变异,且样品中铀元素含量的统计频数属于正偏态分布,这说明该铀尾矿库对其周边土壤产生了一定的污染效应。在统计分析基础上,运用单因子污染指数法与地质累积指数法,并结合Arc GIS空间分析功能对该铀尾矿库周边土壤中铀元素污染程度进行了定量评价,评价结果表明,主要污染区域集中在该铀尾矿库坝址区0~500 m范围内及尾矿库NE侧的应急处理池周围0~100 m内,该评价结果可为铀尾矿库治理及植物修复提供基础数据。     

Analysis of atmospheric aerosols by PIXE: the importance of real time and complementary measurements

Particle-Induced X-ray Emission (PIXE) has been used for more than 30 yr in many urban and background air pollution studies. The technique has certainly contributed to the understanding of source-receptor relationship for aerosol particles as well as to aerosol physics and chemistry. In the last few years, where aerosol issues were strongly linked to global climate change through the relationship between aerosol and atmospheric radiation points to new challenges in atmospheric sciences, where PIXE could play an important role. Also the recognition for the inter-relationship between aerosol and liquid and gas phases in the atmosphere makes important to integrate PIXE aerosol analysis with other complementary measurements. The use of Nephelometers and Aethalometers to measure scattering and absorption of radiation by aerosol particles can be done in parallel with particle filter collection for PIXE analysis. Parallel measurements of trace gases using traditional monitors as well as with new techniques such as Differential Optical Absorption Spectroscopy (DOAS) that can provide concentration of O₃, SO₂, NO₃, NO₂, HCHO, HNO₃, Benzene, Toluene, and Xylene, is also important for both urban and remote aerosol studies. They provide information that allows a much richer interpretation of PIXE data. Recently developed instruments that provide real time aerosol data such as the Tapered Element Oscillating Microbalance (TEOM) PM₁₀ monitor and automatic real time organic and elemental carbon analyzers provide extremely useful data to complement PIXE aerosol analysis. The concentrations of trace elements measured by PIXE comprise only 10–30% of the aerosol mass, leaving the organic aerosol characterization and measurement with an important role. The aerosol source apportionment provided by PIXE analysis can be extended with other aerosol measurements such as scattering and absorption, estimating for example, the radiative impact of each discriminated aerosol source. The aerosol bulk PIXE measurements can be complemented with soluble concentrations provided by Ion Chromatography (IC) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Recent developments in remote sensing techniques and products also enhance significantly regional aerosol studies. Three-dimensional air mass trajectories should be integrated in aerosol studies for urban and remote areas. The applications of these techniques to study urban aerosols from São Paulo and Santiago de Chile have broadened extensively the scientific scope of these studies.     

SPM analysis on groups of single aerosol particles around steel plant

Several methods for preparing samples of dispersed single aeroslo particles used in scanning proton microprobe(SPM) analysis were tested.Many elements such as Al,Si,S,Cl,Ca,Ti,Cr,Mn,Fe,Ni,Cu and Zn in the groups of different single aerosol particles from the Capital Steel Plant area were analyzed by SPM,The distributions of elemental contents in the group of single particles were mapped with three dimensional contour and the isometric.A new approach to study the group of different single aerosol particles for air pollution is developed in the present work.The results are significant to assessing the environmental impact of the dispersed single aerosol particles.     

Detecting small leaks in pipes in nuclear power plants by measuring aerosol parameters

It is found experimentally that when through defects appear in water pipes the concentration and dispersion composition of the aerosols in the room air change. A water or steam leak in a pipe at an early stage of the development of a defect, when the leak still has no effect on the standard operation of the equipment, can be detected by monitoring the aerosol component of the air. The stage where a leak can be detected by aerosol monitoring depends on the background aerosol concentration in the room air, the temperature and pressure in the pipe, and the arrangement of samplers in the monitoring system. The leak-detection method proposed is much more sensitive than moisture content measurements.Translated from Atomnaya Énergiya, Vol. 97, No. 3, pp. 189–195, September, 2004.     

Pollution assessment in the Trancão river basin (Portugal) by PIXE, EDXRF and isotopic analysis

This paper reports on the inorganic contamination assessment of a river basin and local water resources in order to establish quality standards. PIXE was applied to the elemental determination of the freeze-dried water dry residue and EDXRF was used for the evaluation of elemental content of sediments. To infer the water provenance the electrical conductivity was measured as well as the isotopic composition of surface waters using the ¹⁸O/¹⁶O ratio. The combined isotopic and elemental composition information enables to establish dominant contamination contributions from the several tributaries. Moreover, the variability observed for certain parameters, associates them with specific basin regions as for instance, dry residue mass, conductivity and Br, or S, Cl and As or Cr, Ni, Zn and Pb which permit to establish both pollution characterisation and their origin (agriculture, industrial, etc.). At certain locations, enhanced concentrations of elements as Cr, Cu, Zn and Pb are observed both in sediments and in the surface water. The elemental particular associations also permit to characterise pollution sources.     

Clogging of industrial pleated high efficiency particulate air (HEPA) filters in the event of fire

The IRSN and AREVA NC are currently conducting a common interest fire research programme with the aim, among other things, of improving knowledge of clogging of high efficiency particulate air (HEPA) filters and developing an empirical model for clogging of such filters by combustion aerosols. This model must - insofar as possible - be independent of the nature of the fuel and be able to be integrated in a calculation code covering the interaction between the ventilation and the fire. This paper discusses the influence of various “direct” factors such as the filtration velocity, the mass of deposited aerosol per filter area, the diameter and morphology of the combustion particles, the condensate content of the aerosols, and “indirect” factors such as the air flow feeding the fire and its oxygen content, which influence the evolution of the aeraulic resistance of a clogged filter.     

Growth of aerosol particles in a steam environment and its effect on removal

In the present work, growth of cesium iodide aerosols in a mixture of steam and air (non-condensable) is investigated. The condensation rates are calculated including the Kelvin and solute effects. Particle growth to its equilibrium size, with and without energy conservation, is calculated for a range of particle size, temperature and surrounding relative humidity. The time required for the particles to grow to their equilibrium sizes is reported. Finally, the effect of particle growth on the removal of cesium iodide aerosols by gravitational sedimentation is presented.